Tri-n-propylamine (TPA) is, inter alia, an important intermediate for the production of dyes, catalysts and corrosion inhibitors and for use in the pharmaceutical and cosmetics industry (cf., for example, BASF Technical Data Sheet, “Tripropylamine”).
In the amination of n-propanol by means of ammonia, a product mixture of mono-n-propylamine (MPA), di-n-propylamine (DPA) and tri-n-propylamine (TPA) is always obtained. The composition of the amine product mixture formed can largely be controlled via the process parameters in the reaction of propanol. However, the proportion of di-n-propylamine, in particular, in the product mixture is difficult to influence and it is often impossible to produce exactly the amine product mixture wanted by the market.
One possible way of controlling the amine product mixture would be the separate conversion of dialkylamine into trialkylamine by reaction with n-propanol. However, this possibility is not preferred for process engineering and chemical reasons [risk of runaway reactions (uncontrolled temperature rise), safety aspect].
It is known from NL 65644 and the equivalent U.S. Pat. No. 2,574,693 (Shell Dev. Comp.) that monobutylamine can be converted into dibutylamine over an Al2O3 catalyst in the presence of ammonia at high temperatures.
CN 1,325,842 A (Chinese Petro. Chem. Group) teaches the conversion of monoisopropylamine into diisopropylamine over a K/H-beta-zeolite at elevated temperature.